Method for accommodating large movements in a mooring system

ABSTRACT

A method of operating a mooring system exemplified by active mooring devices having attractive attachment elements fixable to a ship&#39;s hull. Each mooring device includes active means for moving the attachment element vertically and in the horizontal plane, and the method involves repositioning the attachment elements in a stepwise manner. The mooring devices also includes a seal for a vaccum attachment element.

RELATED APPLICATIONS

This application is a National Phase in the United States ofPCT/NZ01/00025 and claims the benefit of the New Zealand Application501394 filed Feb. 26, 2000.

TECHNICAL FIELD

The present invention relates to mooring devices for mooring vesselsand, more particularly to a method and mooring system for accommodatinglarge relative movements between two objects moored or secured together.

BACKGROUND ART

One disadvantage of traditional mooring is the necessity to constantlyadjust the mooring lines, particularly when a ship is secured to a fixeddock. This adjustment is to account for movement of the ship in responseto winds, shifting tides, the addition or removal of cargo, and thelike. The combination of high tidal movements and variations in shipdisplacement due to loading can result in a considerable verticalmovement having to be accommodated by the mooring system.

With a mooring device such as that described in the co-pending U.S.application Ser. No. 10/220,009 which is based upon New Zealand Patentapplication No. 501395 (which specification is incorporated herein byreference), a vacuum attachment cup assembly is fixed to the ship'shull. Mechanical means limits movement of mooring robot up and down overthe full extent of the relative vertical travel. This possible movementnecessitates a larger working area, with consequent complication andincreased cost.

Japanese patent abstract publication no. 58206478 describes a mooringdevice and a method of changing the position of a vacuum cup fasteningthe device to the hull. When the device reaches the limits of itsvertical travel the negative pressure in the vacuum cup is raised to adegree permitting the cup to slide without releasing from the hull. Atits limits of travel this passive method therefore offers greatlyreduced mooring forces, making the moored vessel vulnerable to failureof the mooring in adverse conditions of weather and current. The seal ofthe vacuum cup also suffers from abrasion when the cup slides down thehull in this manner and so to avoid regular sliding movement duringoperation the mooring device is provided with increased mechanicaltravel in the vertical direction, with consequent added complication andexpense.

It is an object of the present invention to provide a mooring system andmethod of operating a mooring system for accommodating a large relativevertical movement of a ship when docked. It is a further objective ofthe present invention to provide a mooring system and method and systemfor accommodating a large relative vertical movement of a ship whendocked which overcomes the problems of the prior art.

A still further object of the present invention is the provision of aseal for use in an attachment element for use on a mooring robot.

It is an object of the present invention to address the foregoingproblems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will becomeapparent from the ensuing description which is given by way of exampleonly.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided aseal for a vacuum attachment element, which element can be securedagainst a surface, said seal comprising a circumferential seal member ofsubstantially constant cross-section, said member being mountable in asupport frame rigidly fixed to the attachment element, the seal memberbeing of elastomeric material and including:

-   -   a first sealing face which has an arcuate portion between inner        and outer edges, wherein partial deformation of the said first        sealing face is required before the said inner sealing edge        contacts the surface.

According to another aspect of the present invention there is provided aseal for an attachment element substantially as described above, whereinthe attachment element is part of a mooring robot.

According to another aspect of the present invention there is provided aseal for an attachment element substantially as described above, whereinthe mooring robot releasably fastens to the surface, being a surface ofa first movement object, the mooring robot being mountable to a secondobject, said first object moving in response to the application ofexternal forces, relative to the second object, which movement moves thefirst object from a pre-determined operating position, of the type asdescribed in the co-pending U.S. patent application Ser. No. 10/220,009which is based upon New Zealand Patent application No. 501395.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, which system includesat least a first and second mooring robot, each mooring robot having arobot arm with at least one attachment element for releasable engagementwith a surface, wherein the operating method involves stepwise movementsto re-position the attachment elements between respective starting and afinishing positions in which positions all attachment elements arefastened to the surface, the method including the steps:

-   -   (a) with respect the first mooring robot, releasing all        respective first attachment elements from engagement with the        surface;    -   (b) moving all said first attachment elements, by operation of        the first mooring robot, and re-fastening said elements in the        respective finishing position on the surface;    -   (c) with respect to the second mooring robot, releasing all        respective second attachment elements from engagement with the        surface; and    -   (d) moving all said second attachment elements, by operation of        the second mooring robot, and re-fastening the said elements in        the respective finishing position on the surface.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, including the steps:

-   -   (e) with respect to any further mooring robots releasing all        respective attachment elements from engagement with the surface;        and    -   (f) moving all said respective attachment elements, by operation        of the mooring robot, and re-fastening the said attachment        elements in the respective finishing position on the surface.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the steps are performed sequentially.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the steps (a) and (c) and the steps (b) and (d)in respect of each mooring robot, are performed at the same time.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the mooring robots are mounted to a fixed orfloating dock and the said surface is part of the freeboard of a ship'shull. Alternatively, the mooring robots may be mounted to a floatingvessel for mooring to another vessel or a plate fixed to a fixed orfloating dock.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein each mooring robot includes means for at leasttwo translational degrees of freedom for positioning each attachmentelement. Most preferably the mooring robot provides three-degrees oftranslational freedom for controlling of the position of each attachmentelement and each attachment element is pivotally fixed to the movementmechanism.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the stepwise movement is performed in thevertical direction, allowing the mooring system to accommodate largevertical movements between a ship and its dock. One or two of themooring robots may be at or approaching the

-   limits of vertical travel before the stepwise movement is initiated.    Alternatively, the stepwise movement may be performed in the    horizontal direction for providing movement of the ship in the    fore-and-aft direction.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the method is performed with a mooring systemwhich includes mooring robots as described in the co-pending U.S.application Ser. No. 10/220,009 which is based upon New Zealand Patentapplication No. 501395. Four mooring robots, in first and second pairsare employed, the first pair performing the stepwise movement while thesecond pair remains fastened to the ship. Alternatively both the firstand second pairs may perform the stepwise movement together.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the attachment element is an array of vacuumcups, each vacuum cup having a seal as described according to the firstaspect above.

It will be appreciated that one of the cups of the each mooring robot issufficient to hold that portion of the ship moored, during the operationof the above described method. Thus very large vertical movements of avessel can be accommodated, without the need to re-moor a vessel andwithout risking the security of the mooring system.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from thefollowing description which is given by way of example only and withreference to the accompanying drawings in which:

FIG. 1 is a plan view of a pair of mooring robots, being a firstpreferred arrangement for performing the stepwise movement methodaccording to the present invention;

FIG. 2 is a front elevation illustrating the vertical travel of thevacuum cups of the mooring robots according to FIG. 1;

FIG. 3 is front elevation of the vacuum cups of FIG. 2 at anintermediate stage in the stepping movement of the present invention;

FIG. 4 is a sectional view of a vacuum cup provided with a sealaccording to the present invention in a released position, and

FIG. 5 is a sectional view of a vacuum cup provided with a sealaccording to the present invention fully engaged with a hull surface.

BEST MODES FOR CARRYING OUT THE INVENTION

Referring to FIG. 1 of the drawings, a device for performing the methodof the present invention comprises the first preferred embodiment of amooring system 500, as described in the co-pending U.S. application Ser.No. 10/220,009 which is a national phase of PCT applicationPCT/NZ01/00026 which is based upon New Zealand Patent application No.501395 is illustrated in plan view. The description of the mooring robotand mooring system in the co-pending application is hereby incorporatedby reference.

Other preferred embodiments (not illustrated) include a mooring system500 wherein mooring robots 100 are fixed to the ship S allowing the shipS to be readily fastened to a bearing plate fixed to the dock 50 or toanother ship S. It will be appreciated, however, that this as well asother robot type mooring devices may be employed for performing themethod of the present invention.

In the following description 100 a, 100 b have been used to refer to twospecific examples of the mooring robot 100. FIG. 1 shows a first mooringrobot 100 a and a second mooring robot 100 b fixed to the dock 50 formooring a ship S. The mooring system 500 includes at least two pairs ofmooring robots 100 a, 100 b at spaced positions along a mooring face ofthe dock 50. Each mooring robot 100 has two separate vacuum cups 1pivotally fixed to a robot arm 10 and permitting accurate positionalcontrol of the vacuum cups 1 in three dimensions.

The method of operating the mooring system 500 providing a stepwisemovement is described below with reference to FIG. 2. To accommodate aship S falling or rising relative to the dock 50 (FIG. 1), the vacuumattachment cups 1 fixed to the hull are raised or lowered respectively.It will be appreciated, however, that the same stepwise movement methodapplies to other relative movement such as moving the vacuum attachmentcups 1 from side-to-side in the longitudinal direction, so the followingdescription should not be seen a limiting.

Before mooring the ship S, each vacuum attachment cup 1 is initiallyfree (FIGS l and 4). From initial engagement each cup 1 moves throughpartial engagement (not shown) to complete engagement (FIG. 5) whereinboth the seal 60 and the abutment member 61 are fully compressed.

Referring to FIGS. 2 & 3, the vacuum attachment cups 1 of both mooringrobots (100 a, 100 b) are fixed to the hull at approximately the sameheight H2 and the mooring robots (100 a, 100 b) are able to accommodatea limited degree of vertical travel either side of height H2, between anupper limit of travel at height H1 and a lower limit of travel at H3.The heights H1, H2, H3 are absolute heights relative to the fixed dock50.

When the controls (not shown) of the mooring system 500 detects arequirement to raise the mooring robots 100, due to a mooring robot (100a, 100 b) approaching the limit of its downward travel H3 (througheither a falling tide or the addition of cargo) the stepwise movement ofthe vacuum attachment cups 1 is then initiated.

FIG. 3 shows an intermediate stage during the process of raising thevacuum cups 1 from height H3 to height H4. The vacuum cups 1 of thefirst mooring robot 100 a have been released and the vacuum cups 1raised to height H4. Before moving the vacuum attachment cups 1 they arecompletely released from engagement with the hull (to a position asshown in FIG. 4) thereby allowing the movement to be completed morequickly, as is desired.

Next the vacuum cups 1 of the first mooring robot 100 a are fullyengaged (FIG. 5). On indication of complete engagement, the secondmooring robot 100 b is also raised to height H4 in the same manner.

A first preferred embodiment of a seal 60 according to the presentinvention is shown in FIG. 4

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the steps are performed sequentially.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the steps (a) and (c) and the steps (b) and (d)in respect of each mooring robot, are performed at the same time.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the mooring robots are mounted to a fixed orfloating dock and the said surface is part of the freeboard of a ship'shull. Alternatively, the mooring robots may be mounted to a floatingvessel for mooring to another vessel or a plate fixed to a fixed orfloating dock.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein each mooring robot includes means for at leasttwo translational degrees of freedom for positioning each attachmentelement. Most preferably the mooring robot provides three-degrees oftranslational freedom for controlling of the position of each attachmentelement and each attachment element is pivotally fixed to the movementmechanism.

According to a still further aspect of the present invention there isprovided a method of operating a mooring system, substantially asdescribed above, wherein the stepwise movement is performed in thevertical direction, allowing the mooring system to accommodate largevertical movements between a ship and its dock. One or two of themooring robots may be at or approaching the and FIG. 5. The seal 60provides a continuous seal around the circumference of each vacuum cup1, to which it is rigidly fixed. The seal 60 is made from elastomericmaterial, preferably neoprene. It includes a first arcuate sealing face62 between an inner sealing edge 63 and an outer sealing edge 61.

The seal 60 is optionally used to form the perimeter of each vacuum cup1 used in the method of the present invention. However, it will beappreciated by those skilled in the art that other seals may also beused without departing from the scope of the inventive method.

This configuration of the seal 60 allows it to absorb irregularities inthe surface to which cup 1 is attached. During engagement of the seal60, an initial seal is attained with partial deformation of the outersealing edge 61 at the partial engagement stage (nor shown) before theinner sealing edge 61 contacts the hull of the ship S. With this seal 60there has been found to be a predictable relationship between the amountof deformation at the partial engagement stage and the vacuum applied tothe vacuum cups 1.

In the partial engagement stage the arcuate face 62 is readily adaptedfor sliding engagement with the hull of a ship S or another surface.

The above method of operating a mooring system has been described withreference to vessel moored to a dock, which may be either fixed orfloating. However, it will be appreciated that the dock may be replacedby a vessel (so that there is vessel to vessel docking and relativemovement). Also, it will be appreciated that the mooring system,described herein as affixed to the dock, may be fixed to the vessel. Theoperation is the same except that the surface is a surface affixed tothe dock.

Also, the above method of operating a mooring system has been describedwith reference to vessel moored to a dock. It will, however, beappreciated that another type of vessel or object may be moved relativeto a second object, for example under water, etc without departing fromthe scope of the invention.

Aspects of the present invention have been described by way of exampleonly and it should be appreciated that modifications and additions maybe made thereto without departing from the scope thereof.

1. A method of operating a mooring system, the mooring system comprisingat least a first and a second mooring robot, each mooring robot having arobot arm with an attachment element for releasably fastening to asurface, the first and second robots each having first and secondattachment elements respectively, wherein the operating methodincorporates co-ordinated stepwise movements to re-position eachattachment element between respective spaced apart starting andfinishing positions, in which positions the attachment elements arefastened to the surface, the method comprising the steps: (a) firstly,while maintaining the second attachment element in its respectivestarting position, releasing the first attachment element from thesurface; (b) secondly, while maintaining the second attachment elementin its respective starting position, actuating the first mooring robotto move the first attachment element and re-fasten the first attachmentelement in its respective finishing position; (c) thirdly, whilemaintaining the first attachment element in its respective finishingposition, releasing the second attachment element from the surface; and(d) fourthly, while maintaining the first attachment element in itsrespective finishing position, actuating the second mooring robot tomove the second attachment element and re-fasten the second attachmentelement in its respective finishing position.
 2. The method of claim 1,wherein the mooring robots are mounted to a fixed dock.
 3. The method ofclaim 1, wherein the mooring robots are mounted to a floating dock. 4.The method of claim 1, wherein said surface is part of a freeboard of aship's hull.
 5. The method of claim 1, wherein the mooring robots aremounted to a floating vessel.
 6. The method of claim 1, wherein eachmooring robot provides means for at least two-dimensional movement forpositioning the attachment element.
 7. The method of claim 1, whereineach attractive element is pivotally fixed to a mooring robot providingthree-dimensional translational movement, the mooring robot allowingexternal forces to displace the moored object, and the attachmentelement engaged therewith, by a distance in the horizontal plane from aselected moored position; wherein, separate from its structuralcomponents, the mooring robot comprises resilient restorative meanswhich provide a restorative force acting to restore the attachmentelement to the selected moored position.
 8. The method of claim 7,wherein the three dimensional translational movement comprises movementof the mooring robot about two substantially perpendicular axes ofrotation and translational movement along a translational axis arrangedsubstantially perpendicular to the plane of the two axes of rotation. 9.The method of claim 7, wherein each attractive element is pivotallyfixed to a mooring robot providing three-dimensional translationalmovement, the mooring robot allowing external forces to displace themoored object, and the attachment element engaged therewith, by adistance in the horizontal plank from a selected moored position;wherein, separate from its structural components, the mooring robotcomprises resilient restorative means which provide a restorative forceacting to restore the attachment element to the selected mooredposition.
 10. The method of claim 1, wherein the stepwise movement isperformed in the vertical direction.
 11. The method of claim 1, whereinthe stepwise movement is performed in the horizontal direction.
 12. Themethod of claim 1, wherein in addition to the first and second mooringrobots at least two additional mooring robots are employed, theattachment element of each additional mooring robot remaining fastenedto the surface throughout the stepwise movement of the first and secondrobots.
 13. The method of claim 9, wherein in addition to the first andsecond mooring robots at least two additional mooring robots areemployed, the attachment element of each additional mooring robotremaining fastened to the surface throughout the stepwise movement ofthe first and second robots.
 14. The method of claim 1, wherein eachattachment element comprises an array of vacuum cups, each vacuum cuphaving a circumferential seal including a circumferential seal member ofsubstantially constant cross-section, said member being mountable in asupport frame rigidly fixed to the attachment element, the seal memberbeing of elastomeric material and comprising: a first sealing face whichhas an arcuate portion between first and second sealing edges whereinpartial deformation of the said first sealing face adjacent the firstedge is required before the said second sealing edge contacts thesurface.
 15. The method of claim 7 wherein each attachment elementcomprises an array of vacuum cups, each vacuum cup having acircumferential seal including a circumferential seal member ofsubstantially constant cross-section, said member being mountable in asupport frame rigidly fixed to the attachment element, the seal memberbeing of elastomeric material and comprising: a first sealing face whichhas an arcuate portion between inner and outer edges wherein partialdeformation of the said first sealing face is required before the saidinner sealing edge contacts the surface.
 16. The method of claim 13wherein each attachment element comprises an array of vacuum cups, eachvacuum cup having a circumferential seal a circumferential seal memberof substantially constant cross-section, said member being mountable ina support frame rigidly fixed to the attachment element, the seal memberbeing of elastomeric material and comprising: a first sealing face whichhas an arcuate portion between inner and outer edges wherein partialdeformation of the said first sealing face is required before the saidinner sealing edge contacts the surface.